In a large-scale system that comprises large numbers of servers and storage systems, such as at a data center, a plurality of different communication protocols such as those for a LAN (Local Area Network) and a SAN (Storage Area Network) are used. The LAN is used primarily for communications between a server and a client, and between servers. The SAN is utilized for data I/O (Input/Output) communications between the server and the storage systems.
Because the LAN and the SAN use different communication protocols and physical interfaces, a plurality of types of communication interface circuits must be provided, increasing the number of cables for coupling the respective devices as well. In a case where a redundant configuration is created to enhance reliability, the system configuration becomes that much more complex.
Accordingly, a new communication protocol that integrates a fibre channel over Ethernet (Registered Trademark. This description will be omitted hereinbelow) has been proposed. This communication protocol is called the FCoE (Fibre Channel over Ethernet) (Non-Patent Literature 1, Patent Literature 1). The FCoE is a standard designed so that a frame (a fibre channel frame) constructed using a fibre channel is able to be used over the lossless Ethernet.
FCoE is standard of a communication protocol that makes it possible to send and receive a FC (Fibre Channel) frame over the Ethernet by encapsulating the FC frame in an Ethernet frame. In accordance with this, the plurality of types of communication interface circuits that were required in the past can be converged using a CNA (Converged Network Adapter). The CNA makes it possible to converge the multiple physical ports such as LAN ports and SAN ports together into one port, thereby enabling reduction in the number of physical cables, and making it possible to simplify the configuration of a large-scale system.
In the standard of the Non-Patent Literature 1, all of the FCoE frames must be routed one time through an FCoE switch (also called a Fibre Channel Forwarder) to an internal FC switch, which is a component of the FCoE switch.
In contrast to Non-Patent Literature 1, standards for routing via Ethernet bridges that do not have to go through the FCoE switch are in the process of being devised (Non-Patent Literatures 2 and 3). Non-Patent Literatures 2 and 3 are standard proposals related to a function called a shortcut. The shortcut function makes it possible to directly communicate the FCoE frame that encapsulates the FC frame between the server (FCoE initiator) and the storage system (FCoE target) without going through the FCoE switch. Therefore, FCoE frame traffic that had been focused on a single FCoE switch can be distributed via Ethernet bridges. In accordance with this, it becomes unnecessary to prepare a large number of FCoE switches to ensure bandwidth performance. In addition, a network topology having high performance scalability can be constructed by coupling a large number of Ethernet bridges that do not have FCoE functions.
According to Non-Patent Literatures 2 and 3, at least one entity for managing either the FCoE switch or a fabric is required for a single fabric in order to manage the same FC login information as in the past. In a FCoE network, a configuration in which the Ethernet bridges are sandwiched between the FCoE CNA, which is equivalent to a FC HBA, and a mechanism for managing either the FCoE switch or the fabric, which is equivalent to the FC switch, is permitted. For this reason, the FCoE CNA and the FCoE switch are not always directly coupled.
Technology related to switching to a new HBA in a case where an HBA failure occurs in the FCoE has also been disclosed (Patent Literature 2).